466 MODERN CLASSIFICATION OF INSECTS. 
Burmeister has removed it, however, far from Acanthia, and placed it 
in the family Galgulide. M. Léon Dufour, however, observes that, 
in regard to their external and internal structure and economy, Acan- 
thia, Pelogonus, and Leptopus ought to form a distinct family, whose 
natural situation is at the end of the Geocorisa, and to which Gal- 
gulus should perhaps be united. P. marginatus, the type of the genus, 
is found in the south of France and Spain, on the banks of rivers, 
where it probably feeds upon smaller insects ; it runs very quick, and 
is able to leap well. Its larva, described by Dufour, is somewhat 
smaller than the imago, and more rounded, but it has the same ge- 
neral structure (except in wanting wings) ; it is, however, unabie to 
leap: it inhabits beneath the moist sand, but runs out when the 
ground is shcok; the head is somewhat rostrated. This is the only 
species yet described, but I am acquainted with one of the same size, 
brought from Australia by Mr. Darwin, and a third twice its size. 
-The other genus, which I provisionally place in this family, on ac- 
count of the identical form of the rostrum (fig. 120. 7.), is Aphelo- 
cheirus Westw., founded upon Naucoris estivalis Fab. (vol. i. frontisp. 
fig.’7.), the peculiar structure of which has been overlooked by 
authors, who continue to cite it as a species of Naucoris, from which 
it differs in having simple fore feet, and in the great length and slen- 
derness of the rostrum. In respect, however, to its aquatic habits 
and natatorial hind feet, it assimilates to that genus; thus forming a 
beautiful link between it and Pelogonus. I have had the good fortune 
to capture this interesting insect 7” the river Evenlode, near Ensham, 
Oxon; it swims very fast, using its hind legs chiefly, but crawls very 
slowly, using its four fore feet ; its antennz are much longer than in 
the other water species; all the tarsi are slender and 2-jointed, with 
two slender ungues. My British specimens have but short, rudimen- 
tal, oval hemelytra, like those of the bed bug; but I possess one of 
Bosc’s original specimens, described by Fabricius, not quite so large 
as the others, in which the wings are fully developed. I do not, how- 
ever, on that account, regard the former either as pupz or distinct 
species, but as undeveloped specimens in the imago state. (See my 
memoir on this genus in Loudon’s Mag. Nat. Hist. vol. vi. p. 228.) 
Another remarkable and interesting genus, Leptopus La¢r., consi- 
dered by Latreille, Burmeister, and others as alone forming, with 
Acanthia, a separate family, may here be noticed. Closely allied to 
that genus, in the general form of the body, very prominent eyes, long 
slender feet, it is distinguished by the greater length and slenderness 
